The present invention relates to a projection type image display apparatus in which an enlarged image is projected on a screen to perform an image display, a rear projection type image display apparatus in which the enlarged image is projected on a rear surface of the screen, and a projector optical unit usable in these display devices.
JP-A-5-134213 (document 1), JP-A-2000-162544 (document 2) and JP-A-2002-357768 (document 3) disclose projector optical units in each of which an image is projected onto a screen in a direction oblique to the screen so that a sufficiently enlarged size of the image is obtained on the screen with a short projecting distance.